Radio frequency identification (RFID) devices (e.g., RFID tags, RFID labels, RFID chips, or RFID inlays) are increasingly utilized in a wide variety of applications. For example, an RFID device is typically associated with a retail product for identification and tracking purposes (e.g., attached to a package of the retail product for supply chain management).
The responsibility for applying the RFID devices to, for example, retail product packaging is being placed increasingly on the supplier, with the process of the supplier applying the RFID devices known as source tagging. However, a major supplier may have thousands of different items, which need to have a suitable RFID device and mounting location determined, and this process may have to be repeated when changes are made to the product or packaging.
In general, an antenna of the RFID device may be viewed as having a near field region and a far field region. The near field region refers to a reactive near field (e.g., approximately R≦λ/2π) and a radiating near field (e.g., approximately R<2D2/λ), while the far field region refers to a radiating far-field component (e.g., R>2D2/λ), where R is the distance from the antenna and D is the largest dimension of the antenna. Short-range testing of RFID devices generally involves testing within the near field region, while long-range testing generally involves testing within the far field region.
For a supplier, it may be difficult and/or time consuming to determine the suitable RFID device and optimum mounting for the RFID device on the retail product to provide the desired RFID operation. For example, the location determination may involve mounting the RFID device at a location on the retail product package and performing a corresponding long-range test on the RFID device (e.g., a free space, radiated test of the RFID device at a certain distance with a certain RFID reader power level) to determine the RFID device's performance at that location. This method is time consuming as the RFID device must be repeatedly mounted, tested, and then removed and remounted in another location for the subsequent test to determine the best relative location.
Furthermore, the long-range test must be performed with care to achieve accurate results and prevent skewed results. For example, the results may be adversely affected due to the test environment (e.g., interference from other co-located RFID reader systems) or a flawed test setup (e.g., where the path between the RFID reader and the RFID device has objects nearby, such as the operator carrying out the tests, which can cause reflections that affect tag performance). As a result, there is a need for improved methods for efficiently evaluating the performance of a particular RFID device and its optimum mounting location to an object (e.g., a product or packaged item).